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Biologists to Determine if Rare Plant Deserves Protection

23.09.2009

First, the experts doubted it existed. Then, the federal government protected it under the Endangered Species Act. Now, that protection is in jeopardy, and the status of a rare herbaceous plant lies largely in the work of a team of biologists at Washington and Lee University.

Also known as Virginia sneezeweed, the plant stands about a meter tall and has attractive yellow clusters of flowers.

It's been a long journey for the plant Helenium virginicum, as well as for John Knox, the W&L professor emeritus of biology, and Maryanne Simurda and Paul Cabe, professors of biology.

The journey began in 1974, when Knox stumbled across a plant while doing general field work. He decided to look it up in a reference book and found it was listed as Helenium autumnale, a common plant found all over North America. End of the mystery, he thought. Then he noticed a footnote that said a similar plant was a suspected new species found only in Rockingham and Augusta counties in Virginia, and nowhere else in the world.

"This was in the fine print," said Knox. "But it also stated that the authors of the book doubted that this plant was a distinct species, so even the best botanists in 1974 thought this was a bad hypothesis.

"I thought it was interesting and posed a taxonomic question that I had worked on years ago with fungi, so I decided to try and find the plant and test the hypothesis that this was a new species."

Knox found the putative new plant, and for the next 15 years he conducted a series of studies to determine whether Helenium virginicum, was genetically different from the more common plant, or whether the differences were environmentally-induced.

Working with W&L biology students, he gathered seeds from both plants and raised hundreds of plants in the gardens of Lexington, Va., and studied their development. He found significant differences that were genetically based, and he formed the hypothesis that the two plants had stereotypical habitats. Helenium virginicum grew in sinkhole ponds, unique wetlands that existed on the western side of the Blue Ridge mountains.

"The ponds are pretty places and it's fun and therapeutic to go back to them at all times of the year, year after year. I like to see them in different lights and at different times," said Knox.

The more common plant, Helenium autumnale, could not survive in such an environment, and grew instead along streams, rivers and lakes. "The environmental conditions for the two plants were very different," he explained, "and so we found really strong evidence that this was a new species."

But it wasn't quite enough to convince the U.S. Fish and Wildlife Service. They wanted DNA evidence that the two species of plant were different. So Maryanne Simurda, W&L professor of biology, and an immunologist and molecular geneticist, agreed to sequence the DNA in the two plants to compare them. The results showed even larger differences between the two species.

In 1998, the work at W&L persuaded the federal government to declare Helenium virginicum a new protected species.

But then in 1989, David Marshall, then one of Knox's students at W&L, and now a postdoctoral research associate of evolutionary biology at the University of Connecticut, found a dry museum specimen from Missouri that looked very similar to Helenium virginicum.

Knox drove out to the Ozark Mountains of Missouri, collected more seeds and brought them back to W&L to make comparisons. "This population of the plant had been found in the 1950s, but no one had made the connection with Helenium virginicum," said Knox.

"Finding this population of the plant in Missouri was the most exciting time for me," he added. "I was particularly pleased that my student was involved. He's also collaborated with us on other projects."

After many more rigorous garden studies, Knox formed the hypothesis that this was indeed Helenium virginicum. Again, the U.S. Fish and Wildlife Service wanted DNA evidence, and again Simurda obliged, confirming the hypothesis.

Immediately after the species had become federally protected in 1999, conservation biologists in Missouri searched for and found a cluster of 39 more populations of possible Helenium virginicum.

So now, after all these years, the work begins again. Knox said he relishes the challenge and, newly retired in 2009 after 33 years at W&L, "I'm not really retired at all," he said. The U.S. Fish and Wildlife Service and the Virginia Department of Agriculture and Consumer Services have funded the W&L team to sequence the DNA of the new Missouri plants to determine if they really are Helenium virginicum and to quantify the extent of genetic variation within the species.

The results will help determine whether Helenium virginicum retains its protected status.

"The public will say there are two acres with tens of thousands of Virginia sneezeweed, so this plant is saved," said Knox. "But, if we drain a sinkhole pond, and it never fills with water again, then the plants will go extinct. So I consider our work very important."

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